The present invention relates to an apparatus for matching register marks and punching U-shaped holes for a press plate which is capable of initiating regular printing by a single register mark matching, after setting a press plate for photomechanical process in the multicolor printing machine.
In FIG. 1, there is shown a press plate material (PS plate) in the prior art on which register marks 20 for a photomechanical process is drawn and a pair of pin holes 21, 22 which are punched therein. The register marks 20 are drawn by a vertical automatic register mark drawing device (not shown) at the four locations show, that is, on the right, left, upper and lower edges of an image on the press plate material. The press plate material is loaded on a press plate material loading table and then is centered in the horizontal direction by a centering mechanism, and thereafter it is vacuum contacted to and locked on the press plate loading table through a plurality of air suction holes provided in the loading table. Thereafter, register marks are drawn along a guide by a register mark drawing pen holder in accordance with the size of the press plate material. A pair of pin holes 21 and 22 are punched at the same time. The first pin hole 21 is a standard hole, whereas the second pin hole 22 is a longitudinal hole provided with clearance.
FIG. 2 also illustrates the prior art wherein one end of the press plate materials 1 for each color on which register marks are drawn are inserted into a vice 25 provided on a body 27 of a multicolor printing machine in a direction shown by an arrow a, and after one side of the vice 25 is rotated closed as shown by an arrow b, its end is positioned on the body 27, and then this end of the press plate material is locked on the body 27 of the multicolor printing machine by screws or the like (not shown). Thereafter, the free end of the press plate material 23 is wound around and locked on the body 27 as shown by an arrow c, whereby the press plate is set against the body 27. These procedures are executed for the press plate materials for each color and thus the necessary conditions to start multicolor printing are completed.
In the prior art, at the time of photographically printing the images on an original plate of film on the press plate material, register marks are drawn by a pen or the like on a ground paper on the press plate material and then the register marks on the original film plate are positioned over these register marks, and then printing is done whereby the press plate material is made.
This prior art method of drawing register marks on the press plate material has a disadvantage when the locations of the register marks of each color press plate material used for multicolor printing differ with respect to each other due to location shear caused when the press plate material is loaded on its ground paper. Such location shears can be caused by the pen being angled when register marks are drawn on the press plate material, errors caused by line of sight misalignment through the loop when the register marks of the original film plate are matched to the register marks of the press plate material, mechanical error and the like. Accordingly, the discrepancy in the register marks of the press plate material made as described above is caused when printing is done as indicated above and, as a result of it, it takes a great deal of time to set and locate them on the printing machine without causing color shears of the images. Furthermore, the prior art has additional disadvantages such that the operational efficiency of such a printing machine is extremely low since a number of trial printings have to be made in order to obtain final matching of the images each time the press plate material is changed; as a result, the several hundred sheets of papers are needed every time the press plate material is changed.